Candida albicans, a dimorphic yeast, is among the most commonly encountered human pathogens. Infections caused by Candida range from vaginitis to severe systemic infections in immune compromised patients. The goals of this proposal are: 1) to identify mobile DNA elements in the Candida genome; 2) to use these DNA probes as epidemiologic tools; and 3) to then apply them to basic questions about the biology of the organism. The search for mobile DNA sequences will not be confined to transposable elements but will include any DNA segments associated with elevated frequencies of DNA polymorphisms. The shared properties of movable elements from a variety of organisms suggest methods to isolate them in other species. Using as criteria dispersion, repetition, and absence from related species, a successful screen for such sequences has been conducted. Preliminary results indicate that DNA polymorphisms will be a powerful tool in the typing of C. albicans strains. Candida chromosomes are small enough to be resolved by pulsed field electrophoresis and their lengths are polymorphic as well. It should be possible to combine these facts with single copy DNA polymorphisms and genetic experiments using segregation from fused protoplasts to build a combined physical and genetic map of the organism.